Fluid mixing device



HeavyGrease Aug. 2, 1949. c. R. HETHERINGTON ETAL 2,477,929

' FLUID MIXING DEVICE Fil ed Nov. 12, 1946 LEGEND sl'a FIG.I

Finished Grease l-NVENTORS ATT Patented Aug. 2, 1 949 l a 1 QEELUID'MIXING DEVICE I Charles Ray Hetherington, Bronxville, N. Y., and

Eldred. E. Edwards;- Walnut Creek, Calif., assignorsito." California Research Corporation, San Francisco, Calif., a corporation of Delaware "Application November 12, 194$,SerialNd. 709,290

8- Claims. (01, 259-4)) -This invention relates to afluid'mi'xing device andparticularly refers to one adapted to receive fluids of different physical characteristics, for example viscosity, consistency, shear str'ength, etc; to-mix .them. continuously to forma finished product, for example, grease- I-Ier,etofore, in the manufacture of certain "mixtures fromifiuid or semi-fluid components having widely varying physical characteristics of viscosity and the like it was difiicult to obtain there'- quired intimate degree of contact in continuously operating mixers. This invention comprehends broadly the provision of a multi-stage mixer having separate inlets for the fluids of diiferent characteristics, the mixing being carried out'in sequence and including the provision for circulating an intermediate component from one stage in the sequence to a different stage in the sequence, thereby producing continuous mixtures or blends of materials at a more rapid and eco nomical rate than was possible heretofore. The example of the invention shown and described herein is particularly applicableto the manufacture of soap-thickened compositions which'form the subject matter of the'copending sole application of Charles Ray Hetherington, one ofthe inventors herein, filed November 12, 1946, as Serial No. 709,319. Although it is particularly applicable to this process, it is obvious that the invention is similarly usable in sulfonation, hye drocarbon reacting or other contacting operations wherecomponents of widely varying physical characteristics are to be intimately and con-= tinuously contacted. e e

In the drawing, Figure I is a longitudinal sectional view of: a preferred form of this invention. Figure II is a flow diagram showing the application of this invention to a continuous process for=the manufacture of grease, referred to in the sole application of Charles Ray Hetherington;

mentioned above.

In'Figure I of the drawing, reference numeral 40 designates generally a plate or other suitable type of end member, provided with a central shaftaperture and stufiing box 4|. An opposite end member 42 is spaced from member 40 by means of a cylindrical housing or shell 43, the whole assembly being fastened together with through bolts 44, equally spaced around the periphery of shell 43. 7

Ashaft 41 adapted to be driven by alprime mover (not shown) extends through stuffing box 4i and is received in a central bearing 48 in end member 42. Bearing 48 is provided with aplurality of openings 49 adapted to communicate:

with a central port 50 in housing 42 for-'the pur-- pose ofadmitting the first component; represented'by dotted arrows, substantially uniformlyaround that end of shaft 4'! which is received in bearing 48.-- Mounted, on shaft 4'I,'in thisexample, are three shrouded impellers, respectively designated'5l, 52 and 53,-of the type generally used' in centrifugal pumps. These are spaced along shaft 4'lsby sleeves 54 and 55 andare securedto the shaftby the customarykeys (not shown) and a'threaded nut 56, adjacent the outboard or bearing end of shaft 41.

Within the housing shell 43 diffusion vane as-.

semblies-5'l, 58 and 59 may be providedyof a type similar tothose utilized in turbine type cen'- trifugal pumps. Two inlets 60 and GI are provided in the end member 40 to communicate with an inlet eye of mixing impeller 5i. Inlet Bil-is the inlet for the second component and inlet 6| is the recirculation inlet for the intermediate component. To facilitate this communication, a first diaphragm 62 having a central aperture is positioned within the housing shell 43 adjacent to but spaced from the inner face of endmember 40 and the inlet eye of impeller: 5|. A second of a pumping impeller 52, which is the centerimpeller of the three in this example. The material passing'into the eye of pumping impeller' 52, designated as the finished component, is represented by the solid arrows.

. Desirably, a portion of the fluids or semi-fluids passing through impeller 5| into diffusion vanes 51 recirculate in the spaces between'impeller 5iand diaphragms 62 and 63, as shownby the arrows, to reenter the inlets of that impeller and insure maximum turbulence and mixing.

A fourth diaphragm 61 is position-edon theopposite side of pumping impeller 52 from dia-- phragm 66 and, similar to diaphragm 63, is pro-' vided around its periphery with aperture 68 to cooperate with a fifth diaphragm 69 to redirect at least a portion of the finishedcomponent efiluent'gpassing outwardly from impeller 52 through thespace between diaphragms 61 and to 'a'- central aperturelll in the latter diaphragm which acts finally to direct the finished component into an inlet or eye of the third or mixing impeller 53. The clearance or spacing between diaphragms 66 and 61 and impeller 52 is as close as practicable, to form a seal so that reasonably efiifcient pumping action will be obtained from this impeller. A portion of the finished component passes continously out "of the mixer through outlet '1 I As pointed out above, the first component, represented by dotted arrows, admitted through port 50, enters the eye of mixing impeller 53 opposite from that just described so that mixing of'the first component and the portion of the'finished The speed at which shaft 41 is operated varies, naturally, with the physical characteristics of the first, second, intermediate and finished components and with the design of the impellers employed. When using the mixing device to manufacture lubricating greases containing soap, We *prefer to rotate the shaft at about 1200 R. P.'M. Good dispersions are obtainable with speeds as high as 3600 R. P. M. and as low as 200 R. P. M.

, Referring now to Figure II, wherein the mixer ""of this example is illustrated diagrammatically component which has passedtoimixing'impeller 53 will take place within the" last-named impeller and its corresponding difius'er 59. It 'will be noted from the arrows on the drawing that recirculation from the periphery of impeller 53inwardly to the eyes thereof is facilitatedby -tlie spacing between diaphragm 69, end member 42, andthe adjacent faces of the impeller-shroud.

Two outlets are providedirom' the cylindrical shell 43. The first, designated by'nu'meral H, communicates with diffusion vanes 58 for pumping impeller 52,"and is the outlet for the finished component. The second, designated by numeral '12, communicates with the outlet of mixing impeller'53'and is the outlet for the recirculated intermediate component. Desirably, outlet 12 is provided with-a conduit 13 in-which is mounted valve-means 14, so that the intermediate component, represented by dashed arrows, passing outwardly-from the space surrounding -mrxing impeller--53 may be controllably circulated to inlet 6 l "whereby this intermediate component 'Will be introduced and mingled with the second componententering inlet-BOtopass to the inlet-eye of mixing-impeller 5|. In the eXample-cfFigure-I, the second-component, entering through inlet 60, is represented by dash-dot arrows; the first-component, entering throughinlet '50, by dotted arrowsrthe' intermediate product by dashed arrows; and-thefinishedcomponenhboththat whichflows tor'productstoragethrough'outlet 'H and that whichis'admixedwith the first component, by solid line -arrows, asshown in'the legend-of the drawing.

Abovewe'have described-one exemplific'ation' of ourfiuidmixing device. Describedbelowis'the operation of such' device in grease 'manufacture. a

The mixing'device is first filled with finished grease. Proportioned amounts of heated preformed- 'soapstock (first component) are con tinuously -pumped in through inlet 58. 'Proportioned-v and heated amounts'of mineral-oil (second component) are continuously pumped in through inlet'til. A portion of the'finished-grease (finished component) flowsout through outlet H. Another portion of-the'finished grease (-finished-component) passes -tomixing impeller53 where it is continuously admixed with soap stock (first component) entering the system through inlet -50. The intermediate component, formed by-the intimate -mixing of the finished grease and the soap stock, passes continuously through-outlet 12, throughline 13 intoinlettl. After-entering mixing impeller 5l,--this heavy intermediate component is-intimately mixed and dispersed with mineral oil ('secondcomponent) which (3011-. tinuously enters the system "through inlet 60. The vproduct resulting fromthe intimate disper-. sion of'the mineral oil (second component) and the heavy intermediate component is finished grease (finished component) *to complete the cycle.

;-by' a flow sheet as being applied to the continuous-ma'n'ufacture of grease, preformed soap stock 'fror'ntanksA and B is forced by metering pump I 0 through heater [5 and line l2 into inlet 0f mixer 43. Mineral oil is continuously drawn into the system from tanks C and D by a variable drive metering pump [3 through meter l4 and heater 22, passing into high-speed motordriven mixer 43 through inlet-60. Intermediate product formed, as described'above, in one stage of -mixer 43 is controllably passed through "conduit l3-andvalve M to reenter a cliiferent stage ot-t-h'e mixer through-inletfil. Finished grease passes out of the mixer through outlet 'H and line-26-through strainer 21 and pressur'e'control valve-2'8 to thefinished product storage ta'nlr29. The-processor method involved is claimed in'the copendi'ng sole application of Hetherington cited above.

i From the foregoing it will be apparent that-the exampleillustrated and described'constitutes one form of a continuous multistage grease mixing apparatus adapted separately to receive 'andmix several components in successive stages to form a plurality of grease structures having difierent' physical characteristics, means being provided wherebyycertain "of said grease structuresare recirculated or returned to different "mixing Stages, ultimately to" produce continuouslyafinished' grease having the desired I properties. The number of mixing impellers and the number-of pumpingiinpeilersmay be varied at will and 'the point 'at- "which a given grease structure is taken froma mixingimpeller for circulation, asthrough line 13 ofFigur'e-I, backto' the'impeller with the soap "stock "inlet may be also varied 'as desired. By-the-term grease structure as used in'this specification and appended claims we 'mean a grease, such as a caiciumor soda-base-grease', and-theiika-as they are known'to those'skilled in ;the-art, which saidgrease-may contain more or less soap stock or oil thanis desired in the finished grease.

Although-asingle embodiment of this invention aswell as a single application of that embodiment to -a specific purpose, namely, "the manufacture of "grease-from mineral oil and soap-stock; havebeen-tillustrated and described it is-obvious that other applications of this invention as Well as modifications of i the specific structuredisclosed can -b'e-made without departing therefrom. Acccrdingly, allssuch modifications and changes that come within the 'scope of the appended claims are understood to be embraced thereby.

We claim:

1. 'A- continuous multistage multiple-fluid mixing-device comprising -a housing having separate inlets for fluids of different characteristics, a rotatable shaft "extending into said housing, a plurality of shrouded impellers on said shaft, means in said housing ior 'dire'cting effluent sequentially from. the discharge of one impeller tothe-inletof the next "adjacentimpeller, an can let from said housing communicating with an intermediate impeller discharge, and a second outlet from said housing communicating with the final impeller discharge and adapted to conduct effluent therefrom to the inlet of the first impeller 01 said sequence.

2. A continuous multistage multiple-fluid mixing device according to claim 1, in which said housing is provided with two inlets for separate introductions of two of the fluids to be mixed therein, one inlet communicating with the inlet of the first impeller and the second inlet communicating with the inlet of the last impeller of said sequence.

3. A continuous multistage multiple-fluid mixing device comprising a cylindrical housing, an axial shaft mounted for rotation therein, a plurality oi shrouded impellers on said shaft, means in said housing for directing effluent sequentially from the discharge of one impeller to the inlet of the next adjacent impeller, a fluid outlet for said housing communicating with an intermediate impeller of said sequence, separate inlets for at least two of the fluids to be mixed therein, said inlets leading to separate impellers of said sequence, and conduit means associated with said housing for controllably circulating fluid from an intermediate mixing stage to the inlet of a separate impeller for mixing with a component of the finished product.

4. A continuous multistage multiple-fluid mixing device according to claim 3, with the addition of means in said housing spaced from certain of said impellers to permit fluid recirculation between the discharge and inlet of said impellers.

5. In a continuous multistage grease mixing device having a plurality of mixing stages and adapted to receive soap stock and mineral oil through separate inlets whereby an intermediate component is formed in one stage, outlet and passage means from said stage for continuously and controllably circulating said intermediate component to an inlet adjacent said mineral oil inlet in another stage to be mixed with the mineral oil to form the desired finished grease, passage means for continuously removing a portion of said finished grease from said mixing device, and passage means to circulate the remainder of said finished grease to said first named stage for mixing with incoming soap stock to form the above-named intermediate component.

6. In a continuous multistage grease mixing apparatus having a plurality of mixing stages adapted to receive through separate inlets and disperse soap stock and oil whereby in addition to a finished grease a plurality of intermediate grease structures ar formed, passage and pressuredifferential means for continuously and controllably circulating at least a portion of one of said intermediate grease structures from one stage to an inlet of another stage adjacent to the soap stock inlet to be controllably and continuously dispersed with such soap stock to form another of said intermediate grease structures and passage and pressure difierential means for controllably and continuously passing at least a portion of said last named intermediate grease structure to an inlet adjacent to oil inlet to be continuously and controllably dispersed with said oil and means for controllably and continuously removing said finished grease from said apparatus.

'7. In a continuous multistage mixing apparatus having a plurality of mixing stages adapted to receive through separate inlets and disperse two substances of diverse consistencies, one of which, relative to the other, is of high consistency, whereby there are formed a finished product and a plurality of intermediate products of a consistency intermediate between the substance of higher consistency and that of lower consistency, passage and pressure differential means for continuously and controllably circulating one of said intermediate products from one stage to an inlet of another stage adjacent to the said substance of higher consistency to be continuously mixed with such substance of higher consistency to form an intermediate product and passage and pressure differential means for controllably and continuously passing at least a portion of said last named intermediate products from said stage of formation to an inlet adjacent to the said sub stance of lighter consistency in another mixing stage to be continuously and controllably mixed with said substance of lighter consistency and means for continuously removing from said apparatus the finished product of desired consistency.

8. A continuous multi-stage multiple-fluid mixing device comprising a housing having separate inlets for fluids of different characteristics, a rotatable shaft extending into said housing, three shrouded impellers on said shaft, ported diaphragms in said housing separating said impellers whereby the outermost impellers act as mixers and the center impeller has pump characteristics, said diaphragms and ports therein being arranged to provide means whereby eiiluent from the first mixer impeller is. discharged into the inlet of said pump impeller, which in turn discharges at least a part of its efiluent into the inlet of said second impeller, a finished product outlet for said housing communicating with the discharge of said pump impeller, and conduit means for controllably circulating the effluent from said last-named mixer impeller to the inlet of said first mixer impeller.

CHARLES RAY HEIHERINGTON. ELDRED E. EDWARDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,413,724 Groch Apr. 25,1922 1,819,118 Prelenthner Aug. 18,1931 1,949,696 Schoneborn Mar. 6, 1934 2,071,393 Doherty Feb. 23, 1937 2,239,152 Jacobsen Apr. 22,1941 

